U.S. patent number 8,339,734 [Application Number 12/766,764] was granted by the patent office on 2012-12-25 for magnetic write head having a wrap around trailing shield with an asymetrical side gap.
This patent grant is currently assigned to Hitachi Global Storage Technologies Netherlands B.V.. Invention is credited to Aron Pentek, Yi Zheng.
United States Patent |
8,339,734 |
Pentek , et al. |
December 25, 2012 |
**Please see images for:
( Certificate of Correction ) ** |
Magnetic write head having a wrap around trailing shield with an
asymetrical side gap
Abstract
A magnetic write head having a magnetic write pole with a wrap
around magnetic trailing shield. The wrap around magnetic trailing
shield is separated by a first non-magnetic side gap at a first
side of the write pole and by a second non-magnetic side gap at a
second side of the write pole. The first second non-magnetic side
gap is larger than the first non-magnetic side gap and is
preferably at least twice the thickness of the first non-magnetic
side gap. This design provides additional protection adjacent track
interference at one side of the write pole and additional
protection against magnetic write field loss at the other side of
the write pole.
Inventors: |
Pentek; Aron (San Jose, CA),
Zheng; Yi (San Ramon, CA) |
Assignee: |
Hitachi Global Storage Technologies
Netherlands B.V. (Amsterdam, NL)
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Family
ID: |
44815626 |
Appl.
No.: |
12/766,764 |
Filed: |
April 23, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110261485 A1 |
Oct 27, 2011 |
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Current U.S.
Class: |
360/119.03;
360/125.3; 360/119.04; 360/125.02; 360/319 |
Current CPC
Class: |
G11B
5/1278 (20130101); G11B 5/3116 (20130101); G11B
5/315 (20130101); G11B 5/3146 (20130101); G11B
5/23 (20130101); G11B 5/3163 (20130101) |
Current International
Class: |
G11B
5/235 (20060101); G11B 5/23 (20060101) |
Field of
Search: |
;360/119.01-119.04,125.02,319,125.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2006/201227 |
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Aug 2006 |
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JP |
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2009/043344 |
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Feb 2009 |
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JP |
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2009/050745 |
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May 2009 |
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KR |
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Other References
English-machine translation of JP2009-043344A, Tadaki et al.,
published on Feb. 26, 2009. cited by examiner.
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Primary Examiner: Klimowicz; Will J
Attorney, Agent or Firm: Zilka-Kotab, PC
Claims
What is claimed is:
1. A magnetic write head comprising: a magnetic write pole having
first and second laterally opposed sides and a trailing edge; a
trailing wrap around shield having a trailing portion that is
separated from the trailing edge of the write pole by a
non-magnetic trailing gap and having first and second side
portions, the first side portion being separated from the first
side of the write pole by a first side gap having a thickmess S1
and the second side portion being separated from the second side of
the write pole by a second side gap having a thickness S2, wherein
S2 is greater than S1; wherein the first side gap includes a single
layer of alumina and the second side gap includes two layers of
alumina.
2. A magnetic write head comprising: a magnetic write pole having
first and second laterally opposed sides and a trailing edge; a
trailing wrap around shield having a trailing portion that is
separated from the trailing edge of the write pole by a
non-magnetic trailing gap and having first and second side
portions, the first side portion being separated from the first
side of the write pole by a first side gap having a thickness S1
and the second side portion being separated from the second side of
the write pole by a second side gap having a thickness S2, wherein
S2 is greater than S1; wherein the first side gap includes a single
layer of alumina and the second side gap includes a pair of layer
of alumina separated from one another by a layer of non-magnetic
metal.
3. A magnetic write head comprising: a magnetic write pole having
first and second laterally opposed sides and a trailing edge; a
trailing wrap around shield having a trailing portion that is
separated from the trailing edge of the write pole by a
non-magnetic trailing gap and having first and second side
portions, the first side portion being separated from the first
side of the write pole by a first side gap having a thickness S1
and the second side portion being separated from the second side of
the write pole by a second side gap having a thickness S2, wherein
S2 is greater than S1; wherein the first side gap includes a single
layer of alumina and the second side gap includes a pair of layer
of alumina separated from one another by a layer of Ru or Rh.
4. A magnetic write head comprising: a magnetic write pole having
first and second laterally opposed sides and a trailing edge; a
trailing wrap around shield having a trailing portion that is
separated from the trailing edge of the write pole by a
non-magnetic trailing gap and having first and second side
portions, the first side portion being separated from the first
side of the write pole by a first side gap having a thickness S1
and the second side portion being separated from the second side of
the write pole by a second side gap having a thickness S2, wherein
S2 is greater than S1; wherein the first side gap comprises a layer
of Ru and the second side gap comprises a layer of Ru and a layer
of alumina.
5. A magnetic write head comprising: a magnetic write pole having
first and second laterally opposed sides and a trailing edge; a
trailing wrap around shield having a trailing portion that is
separated from the trailing edge of the write pole by a
non-magnetic trailing nap and having first and second side
portions, the first side portion being separated from the first
side of the write pole by a first side nap having a thickness S1
and the second side portion being separated from the second side of
the write pole by a second side gap having a thickness S2, wherein
S2 is greater than S1; wherein the first side gap includes a layer
of alumina having a thickness of 30-90 nm, and the second side gap
includes a first layer of alumina having a thickness of 30-90 nm
and a second layer of alumina having a thickness of 60-200 nm.
6. A magnetic write head comprising: a magnetic write pole having
first and second laterally opposed sides and a trailing edge; a
trailing wrap around shield having a trailing portion that is
separated from the trailing edge of the write pole by a
non-magnetic trailing gap and having first and second side
portions, the first side portion being separated from the first
side of the write pole by a first side gap having a thickness S1
and the second side portion being separated from the second side of
the write pole by a second side gap having a thickness S2, wherein
S2 is greater than S1; wherein the first side gap includes a layer
of Ru having a thickness of 30-90 nm and the second side gap
includes a layer of Ru having a thickness of 30-90 nm and a layer
of alumina having a thickness of 60-200 nm.
Description
FIELD OF THE INVENTION
The present invention relates to magnetic heads for data recording,
and more particularly to a magnetic write head with a wrap around
trailing shield and having an asymmetrical side gap for reducing
adjacent track interference on one side and reducing write field
loss on the other side.
BACKGROUND OF THE INVENTION
The heart of a computer's long term memory is an assembly that is
referred to as a magnetic disk drive. The magnetic disk drive
includes a rotating magnetic disk, write and read heads that are
suspended by a suspension arm adjacent to a surface of the rotating
magnetic disk and an actuator that swings the suspension arm to
place the read and write heads over selected circular tracks on the
rotating disk. The read and write heads are directly located on a
slider that has an air bearing surface (ABS). The suspension arm
biases the slider toward the surface of the disk, and when the disk
rotates, air adjacent to the disk moves along with the surface of
the disk. The slider flies over the surface of the disk on a
cushion of this moving air. When the slider rides on the air
bearing, the write and read heads are employed for writing magnetic
transitions to and reading magnetic transitions from the rotating
disk. The read and write heads are connected to processing
circuitry that operates according to a computer program to
implement the writing and reading functions.
The write head has traditionally included a coil layer embedded in
first, second and third insulation layers (insulation stack), the
insulation stack being sandwiched between first and second pole
piece layers. A gap is formed between the first and second pole
piece layers by a gap layer at an air bearing surface (ABS) of the
write head and the pole piece layers are connected at a back gap.
Current conducted to the coil layer induces a magnetic flux in the
pole pieces which causes a magnetic field to fringe out at a write
gap at the ABS for the purpose of writing the aforementioned
magnetic transitions in tracks on the moving media, such as in
circular tracks on the aforementioned rotating disk.
Magnetoresistive sensors such as GMR or TMR sensors are employed
for sensing magnetic fields from the rotating magnetic disk. The
sensor includes a nonmagnetic conductive layer, or barrier layer,
sandwiched between first and second ferromagnetic layers, referred
to as a pinned layer and a free layer. First and second leads are
connected to the sensor for conducting a sense current
there-through. The magnetization of the pinned layer is pinned
perpendicular to the air bearing surface (ABS) and the magnetic
moment of the free layer is located parallel to the ABS, but free
to rotate in response to external magnetic fields. The
magnetization of the pinned layer is typically pinned by exchange
coupling with an antiferromagnetic layer.
The thickness of the spacer layer is chosen to be less than the
mean free path of conduction electrons through the sensor. With
this arrangement, a portion of the conduction electrons is
scattered by the interfaces of the spacer layer with each of the
pinned and free layers. When the magnetizations of the pinned and
free layers are parallel with respect to one another, scattering is
minimal and when the magnetizations of the pinned and free layer
are antiparallel, scattering is maximized. Changes in scattering
alter the resistance of the spin valve sensor in proportion to cos
.theta., where .theta. is the angle between the magnetizations of
the pinned and free layers. In a read mode the resistance of the
spin valve sensor changes proportionally to the magnitudes of the
magnetic fields from the rotating disk. When a sense current is
conducted through the spin valve sensor, resistance changes cause
potential changes that are detected and processed as playback
signals.
In order to meet the ever increasing demand for improved data rate
and data capacity, researchers have recently been focusing their
efforts on the development of perpendicular recording systems. A
longitudinal recording system, such as one that incorporates the
write head described above, stores data as magnetic bits oriented
longitudinally along a track in the plane of the surface of the
magnetic disk. This longitudinal data bit is recorded by a fringing
field that forms between the pair of magnetic poles separated by a
write gap.
A perpendicular recording system, by contrast, records data as
magnetizations oriented perpendicular to the plane of the magnetic
disk. The magnetic disk has a magnetically soil underlayer covered
by a thin magnetically hard top layer. The perpendicular write head
has a write pole with a very small cross section and a return pole
having a much larger cross section. A strong, highly concentrated
magnetic field emits from the write pole in a direction
perpendicular to the magnetic disk surface, magnetizing the
magnetically hard top layer. The resulting magnetic flux then
travels through the soft underlayer, returning to the return pole
where it is sufficiently spread out and weak that it will not erase
the signal recorded by the write pole when it passes back through
the magnetically hard top layer on its way back to the return
pole.
In a perpendicular magnetic write head, a trailing magnetic shield
can be used to improve the field gradient of the write field. Such
trailing shields can be formed to wrap around the write pole to
provide side shielding as well. The spacing between the write pole
and these side portions involves a tradeoff between minimizing
adjacent track writing and also minimizing write field leakage to
the side shields.
SUMMARY OF THE INVENTION
The present invention provides a magnetic write head having a
magnetic write pole with a wrap around magnetic trailing shield.
The wrap around magnetic trailing shield is separated from the
write pole by a first non-magnetic side gap at a first side of the
write pole and by a second non-magnetic side gap at a second side
of the write pole. The first second non-magnetic side gap is larger
than the first non-magnetic side gap and is preferably at least
twice the thickness of the first non-magnetic side gap. This design
advantageously provides additional protection adjacent track
interference at one side of the write pole and additional
protection against magnetic write field loss at the other side of
the write pole.
The write head can be manufactured by a process that includes
forming first and second inner side walls and first and second
outer side walls next to the write pole. The inner side walls can
be symmetrical with one another, and likewise the outer side walls
can be symmetrical to one another. Then, mask can be formed over
only one of the outer side walls and a material removal process
such as reactive ion etching or wet etching can be performed to
remove the other outer side wall. This leaves a larger side gap
thickness at one side of the write pole than at the other. A
magnetic trailing wrap around shield can then be formed by a
process such a electroplating.
These and other features and advantages of the invention will be
apparent upon reading of the following detailed description of
preferred embodiments taken in conjunction with the Figures in
which like reference numerals indicate like elements
throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the nature and advantages of this
invention, as well as the preferred mode of use, reference should
be made to the following detailed description read in conjunction
with the accompanying drawings which are not to scale.
FIG. 1 is a schematic illustration of a disk drive system in which
the invention might be embodied;
FIG. 2 is an ABS view of a slider, taken from line 2-2 of FIG. 1,
illustrating the location of a magnetic head thereon; and
FIG. 3 is a side cross sectional view of a magnetic write head
according to an embodiment of the present invention;
FIG. 4 is an ABS view of a portion of the write head of FIG. 3, as
viewed from line 4-4 of FIG. 3;
FIGS. 5-16 are views along a plane parallel with the ABS of a
portion of a write head in various intermediate stages of
manufacture illustrating a method of manufacturing a magnetic write
head according to an embodiment of the invention;
FIGS. 17-23 are views along a plane parallel with the ABS of a
portion of a write head in various intermediate stages of
manufacture illustrating a method of manufacturing a magnetic write
head according to an alternate embodiment of the invention;
FIGS. 24-35 are views along a plane parallel with the ABS of a
portion of a write head in various intermediate stages of
manufacture illustrating a method of manufacturing a magnetic write
head according to yet another embodiment of the invention; and
FIG. 36 is a schematic view illustrating the implementation of an
embodiment of the invention in a data recording system in which
data tracks overlap one another.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The following description is of the best embodiments presently
contemplated for carrying out this invention. This description is
made for the purpose of illustrating the general principles of this
invention and is not meant to limit the inventive concepts claimed
herein.
Referring now to FIG. 1, there is shown a disk drive 100 embodying
this invention. As shown in FIG. 1, at least one rotatable magnetic
disk 112 is supported on a spindle 114 and rotated by a disk drive
motor 118. The magnetic recording on each disk is in the form of
annular patterns of concentric data tracks (not shown) on the
magnetic disk 112.
At least one slider 113 is positioned near the magnetic disk 112,
each slider 113 supporting one or more magnetic head assemblies
121. As the magnetic disk rotates, the slider 113 moves radially in
and out over the disk surface 122 so that the magnetic head
assembly 121 may access different tracks of the magnetic disk where
desired data are written. Each slider 113 is attached to an
actuator arm 119 by way of a suspension 115. The suspension 115
provides a slight spring force which biases slider 113 against the
disk surface 122. Each actuator arm 119 is attached to an actuator
means 127. The actuator means 127 as shown in FIG. 1 may be a voice
coil motor (VCM). The VCM comprises a coil movable within a fixed
magnetic field, the direction and speed of the coil movements being
controlled by the motor current signals supplied by controller
129.
During operation of the disk storage system, the rotation of the
magnetic disk 112 generates an air bearing between the slider 113
and the disk surface 122 which exerts an upward force or lift on
the slider. The air bearing thus counter-balances the slight spring
force of suspension 115 and supports slider 113 off and slightly
above the disk surface by a small, substantially constant spacing
during normal operation.
The various components of the disk storage system are controlled in
operation by control signals generated by control unit 129, such as
access control signals and internal clock signals. Typically, the
control unit 129 comprises logic control circuits, storage means
and a microprocessor. The control unit 129 generates control
signals to control various system operations such as drive motor
control signals on line 123 and head position and seek control
signals on line 128. The control signals on line 128 provide the
desired current profiles to optimally move and position slider 113
to the desired data track on disk 112. Write and read signals are
communicated to and from write and read heads 121 by way of
recording channel 125.
With reference to FIG. 2, the orientation of the magnetic head 121
in a slider 113 can be seen in more detail. FIG. 2 is an ABS view
of the slider 113, and as can be seen the magnetic head including
an inductive write head and a read sensor, is located at a trailing
edge of the slider. The above description of a typical magnetic
disk storage system, and the accompanying illustration of FIG. 1
are for representation purposes only. It should be apparent that
disk storage systems may contain a large number of disks and
actuators, and each actuator may support a number of sliders.
With reference now to FIG. 3, the invention can be embodied in a
magnetic write head such as, for example; the write head 302,
depicted in side cross sectional view in FIG. 3. The magnetic write
head 302 includes a magnetic write pole 304 and a magnetic return
pole 306. A magnetic back gap layer 308 and magnetic shaping layer
310 magnetically connect the return pole 306 with the write pole
304 at a location removed from an air bearing surface (ABS).
An electrically conductive, non-magnetic write coil 318 passes
between the write pole 304 and return pole 306 and may also pass
above the write pole 304. The write coil 318 can sit on top of a
non-magnetic, electrically insulating material 322 and is also
embedded in a non-magnetic, electrically insulating material 320
such as alumina and or hard baked photoresist.
During operation, an electrical current flowing through the coil
318 induces a magnetic field that results in a magnetic flux
flowing through the write pole 304. This causes a magnetic field to
be emitted from the write pole 304 toward a magnetic medium such as
the magnetic medium 122 shown in FIG. 1. This magnetic write field
flows through the medium to return to the return pole 306 which has
a sufficiently large cross section that it does not erase the
magnetic bit written by the write pole 304.
In order to increase the write field gradient (and thereby increase
switching speed), the write head 302 also includes a magnetic
trailing shield 312. This trailing shield 312 is separated from the
write pole 304 by a non-magnetic trailing gap layer 408. The write
pole 304 may also be connected with a trailing return pole 316 that
connects the trailing shield 312 with the back portion of the write
head 302, such as the back portion of the shaping layer 310.
FIG. 4 shows an ABS view of a portion of the write head 302 as seen
from line 4-4 of FIG. 3. As can be seen, the trailing shield 312 is
a wrap-around-trailing shield that has side portions 402, 404 that
wrap around the sides of the write pole 304 to provide a side
shielding function. This side shielding is useful in preventing
adjacent track writing by absorbing magnetic fields that might emit
from the sides of the write pole 304. The trailing portion of the
write head 304 is separated from the trailing shield 312 by a
non-magnetic gap layer 408, which can be a non-magnetic metal such
a Ru or Rh. The side portions 402 404 of the shield 312 are
separated from the write pole 304 by non-magnetic side gap layers
406, 410, and also possibly by the trailing gap layer 408 in the
side region.
It has been found that adjacent track writing occurs much more
readily at one side of the write head than the other. It is when
designing a write head having a trailing, wrap-around shield it is
desirable that the size of the non-magnetic side gap be balanced
between two competing factors. The side gap should be small enough
to prevent stray field from the write pole from writing to adjacent
data tracks. In addition, a small side gap also improves field
gradient at the track edge. On the other hand the size of the side
gap should be large enough to prevent magnetic write field from
leaking to the side portions of the shield (which would decrease
write field strength to the media).
In order optimize both of these competing factors in a magnetic
head wherein adjacent track interference occurs in an asymmetrical
manner, the present invention provides a write head having
asymmetrical side gaps. As seen in FIG. 4, the write head has a
side gap S1 that is defined by thickness of the non-magnetic gap
layer 406 (and optionally by the additional gap layer 408), and has
a second gap thickness S2 that is defined by thickness of the side
gap 410 (and optionally the additional gap layer 408). As can be
seen, S1 is significantly smaller than S2. Preferably, S2 is at
least twice S1. In this way, the additional side gap thickness S2
can be provided to reduce the amount of write field lost to the
side portion 404 of the shield 312, and the smaller side gap S1 can
be provided to give additional protection adjacent track writing on
the side where adjacent track writing is more of a problem. Methods
for manufacturing such a write head and for carefully controlling
the thickness of these different side gaps S1 and S2 are described
herein below.
FIGS. 5-16 illustrate a method for manufacturing a write head
according to a possible embodiment of the invention. With
particular reference to FIG. 5, a substrate 502 is provided. This
substrate 502 can include the layer 302 of FIG. 3 and also all or a
portion of the shaping layer 310 of FIG. 3. A layer of magnetic
write pole material 504 is deposited over the substrate 502. While
the magnetic write pole layer 504 can be a single layer of high
Bsat magnetic material such a CoFe, it is preferably formed as
laminations of layer of high Bsat magnetic material separated by
thin layer of non-magnetic material. One or more mask layers 506
are then deposited over the magnetic write pole material layer 504.
While the mask layer 506 can be of various structures, the mask
structure preferably includes a hard mask layer 508, which may be
one or more layers of, for example alumina, diamond like carbon or
some other material. An image transfer layer 510 is then deposited
over the hard mask layer 508. The image transfer layer 510 can be a
soluble polyimide material such as DURIMIDE.RTM.. A second hard
mask (or RIE mask 512 is then deposited over the image transfer
layer 510. This layer 512 can be a material such as SiO.sub.2, or
some other suitable material. A bottom anti-reflective coating
(BARC) layer 514 is then deposited over the second hard mask layer
512. The BARC layer 514 can be a material such as DURIMIDE.RTM..
Finally, a layer of photoresist 516 is deposited over the BARC
layer 514. The photoresist layer is then photolithographically
patterned and developed to form a mask having a shape to define a
write pole. Then a series of ion milling and reactive ion etching
processes are performed to transfer the image of the photoresist
mask 516 onto the underlying mask layers 514, 512, 510, 508 to form
a structure such as that shown in FIG. 6.
An ion milling process can then be performed to remove portions of
the write pole material 504 that are not protected by the mask 506,
leaving a structure such as that shown in FIG. 7. The ion milling
process can be performed at one or more angles relative to normal
in order to form the write pole material 504 with a trapezoidal
shape having tapered side walls as shown in FIG. 7. The ion milling
process may also remove many of the layers of the mask 506 (FIG. 6)
and may leave only the hard mask layer 508 after ion milling, as
shown in FIG. 7. Masking layers not removed by the ion mill can be
stripped using NMP or O.sub.2 RIE.
Then, as shown in FIG. 8, a layer of non-magnetic material 802 can
be deposited. This layer 802 can be a first layer of alumina
deposited by a conformal material deposition process such as atomic
layer deposition (ALD). The ALD layer 802 is preferably deposited
to a thickness of 30-90 nm.
An ion milling is then performed to preferentially remove
horizontally disposed portions of the ALD layer 802 to from a first
(or inner) set of non-magnetic side gap walls 802 as shown in FIG.
9. A reactive ion etching can then be performed to remove the
remaining hard mask 508, leaving a structure such as that shown in
FIG. 10.
Then, with reference to FIG. 11, a non-magnetic trailing gap layer
1102 is deposited. This layer 1102 can be constructed of, for
example, Ru or Rh, and is deposited to a thickness that is chosen
to define a trailing gap thickness. Then, another thick layer of
non-magnetic material 1202 is deposited. Like the other layer 802,
this layer can also be constructed of alumina deposited by a
conformal deposition process such as Atomic Layer Deposition (ALD).
This second ALD layer 1202 can be deposited to a thickness of
60-200 nm. Another ion milling can then be performed to
preferentially remove horizontally disposed portions of the second
ALD layer 1202, stopping when the metal gap layer 1102 has been
exposed, as shown in FIG. 13. This results in a second (outer) set
of side walls 1202 being formed. As can be seen, the first set of
side walls 802 is separated from the second set of side walls 1202
by the non-magnetic metal gap layer 1102.
Then, with reference to FIG. 14, a photoresist mask structure 1402
is formed so as to cover one side of the structure while leaving
the other half uncovered. Therefore, one of the outer side gap
layers 1202(a) is covered by the mask 1402, while the other side
gap layer 1202(b) is not. Then, a Reactive Ion Etching (RIE) or a
wet etch process is performed to remove the exposed outer side wall
1202(b), leaving a structure such as that shown in FIG. 15. The
photoresist mask 1402 can then be removed. A magnetic electrically
conductive seed layer 1401 is deposited. This seed layer can be
CoFe or CoFeNi alloy. Then, another mask structure can be 1602
formed such as shown in FIG. 16 to provide an electroplating frame
mask. The electroplating frame mask 1602 is formed with an opening
that is configured to define a trailing magnetic shield. A magnetic
material 1604 can then be electroplated into the opening to define
a trailing-wrap-around magnetic shield.
FIGS. 17-23 illustrate an alternative method for constructing a
magnetic write pole having a trailing-wrap-around magnetic shield
with asymmetrical side gaps. Starting with a structure such as that
described above with reference to FIG. 7, a layer of non-magnetic
metal 1702 is deposited, as shown in FIG. 17. This non-magnetic
metal is preferably a material that is resistant to a material
removal process that can be used to remove alumina, for reasons
that will become apparent below. The non-magnetic metal 1702 is
preferably Ru and is preferably deposited by atomic vapor
deposition to a thickness of 30-60 nm.
Then, with reference to FIG. 18 a layer of alumina 1802 is
deposited, preferably by atomic layer deposition. This alumina
layer 1802 is preferably deposited to a thickness of 60-200 nm. An
ion milling is then performed to a portion of the layers 1802,
1702, using an end point detection scheme to terminate ion milling
when the hard mask 508 has been reached. Then a reactive ion
etching (RIE) can be performed to remove the remaining hard mask
508, leaving a structure such as that shown in FIG. 19.
Then, with reference to FIG. 20, a mask structure 2002 is formed so
as to cover half of the structure thus formed, leaving the other
half uncovered. A reactive ion material removal process can then be
performed to remove exposed portions of the alumina layer 1802,
leaving a structure such as that shown in FIG. 21. The material
removal process can be a reactive ion etching performed in a
chlorine chemistry or can be a wet etch designed to remove
alumina.
The mask 2002 can then be removed and a thin layer of non-magnetic
metal such as Ru or Rh 2202 can be deposited to a thickness chosen
to define a trailing gap thickness. Then, as shown in FIG. 23, an
electroplating frame mask 2302 can be formed having opening
configured to define a trailing-wrap-around magnetic shield as
shown in FIG. 23. A magnetic material 2304 can then be
electroplated into the opening to form a trailing-wrap-around
magnetic shield. The underlying metal gap layer 2202 can be used as
an electroplating seed.
FIGS. 24-35 illustrate yet another possible method for
manufacturing a magnetic write head according to an embodiment of
the invention, wherein the write pole is formed by a damascene
process. With particular reference to FIG. 24, a substrate 2402 is
provided. Again this substrate 2402 can be a portion of the
non-magnetic layer 320 and shaping layer 310. A RIE stop layer 2401
is deposited over the substrate 2402. The RIE stop layer can be a
material such as Cr, NiCr, or Ru. A RIEable fill layer 2404 is
deposited over the RIE stop layer 2401. The RIEable fill layer can
be a material such as Al.sub.2O.sub.3, SiO.sub.2 and is deposited
to a thickness that is at least as thick as a desired finished
write pole. Then, a metal mask 2406 is formed over the RIEable fill
layer 2404, the mask having an opening configured to define a write
pole, but slightly larger than the write pole for reasons that will
become apparent below. This metal mask can be formed by a
traditional liftoff or other method well known to those skilled in
the art. The metal mask can be a material such as NiCr that has a
high RIE selectivity to the RIEable fill layer.
With reference now to FIG. 25, a Reactive Ion Etching (RIE) is
performed to remove portions of the RIEable fill layer 2404 that
are exposed by the opening in the mask 2406. The RIE can be
performed in such a manner as to form an opening with tapered side
walls in the fill layer 2404. A layer of non-magnetic material 1602
is deposited to reduce the width of the opening. The non-magnetic
material 1602 can be Ru and is preferably deposited by atomic vapor
deposition to a thickness of 30-60 nm. This reduces the track width
of the sensor, as will be seen. A magnetic material can then be
electroplated into the opening to form a write pole 1702, using the
non-magnetic layer 2602 as an electroplating seed and leaving a
structure such as that shown in FIG. 27. A chemical mechanical
polishing and ion milling can then be performed to form a structure
such as that shown in FIG. 28, where the fill layer 2404 is exposed
at the sides of the write pole 2702.
A reactive ion etching can then be performed to remove the
remaining RIEable fill layer, leaving a structure such as that
shown in FIG. 29. Alternatively a wet etch can also be used to
remove the fill layer 2404. Then, as shown in FIG. 30, an
additional layer of non-magnetic material 3004 such as Ru can be
deposited to provide additional width to the inner side walls
formed by the layers 2602, and to provide an end point detection
layer of a subsequent ion milling process. This additional layer
3004 can be Ru deposited by atomic vapor deposition and can be
deposited to a thickness of anywhere from 0-40 nm, depending upon
design requirements. It should also be pointed, however, out that
the deposition of this additional layer 3004 is optional.
With reference now to FIG. 31 a thicker layer of alumina 3102 is
deposited, preferably by atomic layer deposition (ALD). This layer
can be deposited to a thickness of 60-200 nm. An ion milling is
then performed using the Ru layer 3004 as an end point detection
layer. The ion milling therefore, stops when the Ru layer 3004 has
been removed. This leaves a structure such as that shown in FIG.
32.
Then, with reference to FIG. 33 a mask is formed over one side of
the write pole and side gap layers 3702, 2602, 3004, 3002, leaving
the other side uncovered. Then, a reactive ion etching is performed
to remove the exposed outer gap layer 3002(b) (FIG. 33) leaving the
covered outer layer 3002(a) intact as shown in FIG. 34.
Alternatively, a wet etch process could also be used to remove the
exposed outer gap layer 3002(b). Then, with reference to FIG. 35, a
non-magnetic, electrically conductive seed layer 3506 is deposited
to provide a trailing gap layer as well as an electroplating seed.
A layer of magnetic material 3504 is then electroplated to form a
trailing-wrap-around magnetic shield.
As mentioned above, the use of an asymmetrical wrap-around-trailing
shield can be advantageous in certain magnetic data recording
systems. One such system in which an asymmetrical
wrap-around-trailing shield can be particularly advantageous is a
system wherein data track intentionally overlap one another, also
referred to as a "shingle" recording system.
The use of an asymmetrical wrap-around-trailing shield in such a
shingle recording system can be better understood with reference to
FIG. 36. As seen in FIG. 36, a write pole 304 records tracks of
data (n) 3602, (n+1) 3604, (n+2) 3606 etc. that overlap one
another. Overlapping the data tracks in this manner achieves a
significant increase in data track density, thereby improving data
density. The writing occurs at the trailing edge of the write pole
304 and occurs more significantly at one side 3608 of the write
pole 304 than at the other side 3610.
The use of an asymmetrical wrap-around-trailing shield 312 can help
to facilitate recording in such a shingle recording system by
increasing side shielding at one side 3610 of the write pole
(thereby minimizing the write of data to adjacent tracks (e.g. n+1,
3604) and also maximizing the write field and write field gradient
at the other side 3608 of the write pole 304.
While various embodiments have been described above, it should be
understood that they have been presented by way of example only,
and not limitation. Other embodiments falling within the scope of
the invention may also become apparent to those skilled in the art.
Thus, the breadth and scope of the invention should not be limited
by any of the above-described exemplary embodiments, but should be
defined only in accordance with the following claims and their
equivalents.
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